In an image forming apparatus, an image forming unit including a photoconductor and a scanner unit is supported by sidewalls disposed on either side thereof. For example, a related-art image forming apparatus has a structure in which a sheet-metal frame and a resin frame which are overlapped in their thickness direction (in the right-left direction) to form a sidewall, the sheet-metal frame supports a photoconductor and a scanner unit to determine the relative position therebetween, and the resin frame supports a belt for conveying a recording medium, a fixing unit for fixing a toner image on the recording medium, and a discharge unit for discharging the recording medium. That is, since it is difficult to form supporting portions for supporting a number of modules in the sheet-metal frame through sheet metal processing, the sheet-metal frame supports only modules that require positional accuracy, while the resin frame supports the other modules.
In the structure described above, the resin frame defines the entire height of the sidewall, and the sheet-metal frame is disposed only in the upper part of the sidewall. The upper ends of a pair of upper frames are coupled via a scanner supporting plate, the intermediate parts of a pair of resin frames extending below the sheet-metal frame are coupled via a base plate, and the lower ends of the frames are coupled via a bottom plate.